1. Field of the Invention
The present invention is related to methods and systems capable of reducing obstruction of the upper airway in obstructive sleep apnea (OSA) and snore patients. More particularly, the present invention relates to an oral apparatus that prevents mouth breathing and also provides negative pressure in the oral cavity.
2. Prior Art
Obstructive sleep apnea (OSA) is a condition in which repeated collapses in the patient's airway during inhalation causes a cessation of breathing during sleep. During inhalation, air pressure in the lungs and respiratory passages is reduced. If during this time, the tone of the muscles in the upper-airway is reduced, the airway tends to collapse. As the airway begins to occlude prior to an apnea episode, the patient often begins to snore. Snoring is an effort to try to combat the collapsed airway. These obstructions occur in different locations along the respiratory pathway in different patients, but the two common locations are the oropharynx or the nasopharynx.
People with moderate to severe OSA experience daytime sleepiness, fatigue, and poor concentration. In addition to these immediate problems, research has shown that patients with OSA use more medical resources, have an increased risk of medical disability, and finally have a higher mortality rate. Patients with severe OSA are estimated to have a three to six fold increased risk of mortality considering all causes. OSA is also implicated in many cardiovascular conditions, such as systemic hypertension and some degree of pulmonary hypertension. It is associated with an increased risk for myocardial infarction, cerebrovascular disease, and cardiac arrhythmia. OSA causes excessive daytime sleepiness due to interrupted sleeping pattern at night which leads to inability to concentrate. Patients' daily functions are impaired as their neuro-cognitive function is compromised. They are more likely to make errors and run into accidents. Therefore, OSA is a significant medical condition with serious negative outcomes if left untreated.
There are several current treatment options for OSA patients. Oral appliances are used to treat mild OSA, but they often don't work well and cause damage to gums and teeth. Several types of surgery are used to treat OSA, however, surgical options are invasive, expensive and painful with recovery periods up to 6 months. The most common treatment for moderate to severe sleep apnea in adults is CPAP, which has 96% market share in OSA therapeutics. A CPAP machine consists of a mask, a pump and a humidifier. The device continuously blows pressurized air into the patient's nose to keep the airway open during sleep. CPAP is quite effective; however, it has unpleasant side effects such as dry throat and nose congestion. Patients who use CPAP often feel bloated in the morning and experience headaches. The machine is noisy and uncomfortable for the user and their partner. CPAP is currently the first-line and gold standard treatment, but it suffers low compliance due to significant side effects.
It has been proposed to apply a negative pressure to the patient's oral cavity to pull the tongue and soft palate forward to maintain the patency of the airway, as an improvement over CPAP, for example, U.S. patent and Patent Publication Nos. U.S. Pat. No. 5,957,133, 2005/0166928, and 2006/0096600. While promising in theory, these prior arts comprise relatively large structures to engage the teeth and/or to retain the tongue. Moreover, negative pressure is applied directly on the soft tissues of the tongue to hold the tongue within the cavity. These approaches tend to occupy a lot of space in the oral cavity, which may cause discomfort and damage to large area of teeth, gum, and soft tissues. At the same time, the presence of such larger devices may induce excess saliva secretion and elicit the gag reflex. The other major disadvantage of these approaches is that the oral devices are anatomically dependent, requiring special technicians to customize the interface for each individual patient.
Therefore, it is one objective of the present invention to provide alternative and improved methods and apparatus for treating obstructive sleep apnea and snoring. It is another objective of the present invention to provide minimally intrusive methods and apparatus with components that are comfortable and convenient to use. It is still an objective of the present invention to provide methods and apparatus that avoid contacting the portions of the oral cavity that cause discomfort, induce excess saliva, and trigger the gag reflex. The methods and apparatus should be simple to implement and to significantly improve patency of a patient's airway during sleep. At least some of these objectives will be met by the inventions described hereinafter.